Rotary switch



Aug. 17, 1937. E. UHLE Y ROTARY SWITCH Filed Dec.-4, 1955 INVENTOR ORNEYPatented Aug. 17, 1937 UNITED STATES ROTARY SWITCH Emil Uhle, Naugatuck,

Conn., assignor to The Lewis'Engineering Company, Naugatuck, Conn., acorporation of Connecticut Application December 4, 1933, Serial No.700,783

9 Claims.

This invention relates to electric switches, and more particularly, to aswitch of the type adapted to selectively connect a plurality ofthermo-' couples or the like to an indicating instrument.

An object of this invention is to provide an.

improved switch of the kind referred to having a low resistance so asnot to appreciably affect the currents to be indicated and yet be simpleand durable in construction and certain in operation. a

A feature of this invention is the provision of cylindrical contactsdriven in or molded in the insulating disk forming the main body andback of the switchf The contacts have integral portions, preferablyflattened, extending from the rear of the disk and provided with bindingscrews to which the ends of the wires forming the cir-' cuits to becontrolled by the switch are fastened. By having the contacts andterminals made of one piece, there is avoided danger of poor contactwhich might exist if these parts were made separate pieces, and whichmight vary the current passing to the indicating instrument and causethe latter to give a false reading. Another'featu're of this inventionis the provision of a bearing for the shaft carrying the switcharms-which bearing is driven in or molded in the disk of insulationabove referred to and constitutes the sole bearing for the shaft. Thehearing is provided with a screw having a guide pin on its inner endwhich extends into an annular groove in the shaft and limits thelongitudinal movement of the shaft.

Another feature of the invention is the provi sion of a detent devicefor the shaft to hold the shaft against casual movement and to hold theswitch arms in proper engagement with the contacts. The detent device,according to the present invention, comprises a notched disk carried bythe shaft and a spring mounted on a post carried by the disk ofinsulating material. The

casing and dial for the switch are removably connected to the disk ofinsulating material and, with the detent and other parts of the switchls-arranged as disclosed herein, the switch may be completelyassembledand tested before the easing is applied to the disk or main insulatingbody of the switch.

' Other features and advantages will hereinafter appear.

In the accompanying drawing Figure 1 is a-vertical section taken throughthe middle of the switch.

Fig. 2 is a transverse section taken'on the line 22 of Fig. 1.

Fig. 3 is atransverse section taken on the line 33 of Fig. 1.

Fig. 4 is a rear view of the insulating disk forming the main body ofthe switch, showing the outline of the casing in dot-and-dash lines. 5

Fig. 5 is a sectional view taken on the line 55 of Fig. 1, the casingbeing omitted and its outline shown in dot-and-dash lines.

Fig. 6 is a front view of the switch with the casing and finger-pieceattached.

Fig. 7 is an elevation of one of the contacts, showing it provided withknurling to prevent its turning in the disk.

As shown in the accompanying drawing, the switch of the presentinvention comprises a disk 15 ID of insulating material forming the mainbody and back of the switch; The switch is of the rotary type anddesigned to selectively connect thermocouples or othercondition-responsive devices to an indicating instrument. 20

The disk In is provided with a central aperture H (see Fig. 4) intowhich a bearing I2 is driven. This bearing has a flange l3 engaging thefront face of the disk ID. The bearing I2 receives and supports a shaftII which carries g5 switch arms l5 and I6, and has at its outer end ahandle or finger-piece I 1. The bearing I2 forms the sole support forthe shaft l4 and is provided with a locking screw l8, the end of whichextends into a circumferential groove in the shaft 30 I4 and holds theshaft against endwise movement in the bearing and insulating disk ID.The switch has a housing is, which may be of insulating material ormetal as desired, engaging a. flange 20 on the disk l0 and having at itsother end a dial 35 or face 2| through which the shaft l4 extends.

The switch arms l5 and I6 are not carried directly by the shaft I4 butare carried by insulating disks 22 secured to a disk 23 fastened ontothe shaft ll.

The arms 15 and 16 are insulated from each other and fromthe shaft H.The switch arms are U-shaped and are superposed and nested one withinthe other, the switch arm l5 being shorter than the switch arm l6.

The switch of the present invention is of the two-pole type, connecting,as it does, both wires leading from a thermocouple to both wires leadingto the indicating instrument. The wires, from the indicating instrumentare broughtto 50* terminal pieces or binding posts 24 and 25 projectingfrom the rear face of the disk Ill. These binding posts 24 and 25 areconnected respecl tively to inner and outer semicircular contact bars 26and 21 lying on the front face of the 55 disk of insulation I3 and beingheld in place thereon by pins 28 driven into the disk Ill. The switcharms l5 and 96 respectively continuously engage the semicircular contactbars 23 and 21.

According to the present invention, QDPOsite the contact bars 26 and 21!the disk ill is provided with two concentric rows of contacts 29 and 30,the contacts 29 being in position to be engaged by the switch arm l5while the contacts 30 are in position to be engaged by the switch armi3. These contacts are cylindrical and are driven into the disk it untiltheir forward ends project slightly beyond the surface of the disk.

The contacts 30 are made long enough so that when their forward ends arein proper positions, their rearward integral ends are made to extend farenough beyond the rear face of the disk 10 to constitute terminal piecesand binding posts for the wires leading from the thermocouples or thelike. To facilitate the attachment of the wires, the contact members 33have flattened surfaces 3i and screw-threaded apertures to receivebinding screws 32 and 33.

The binding screws 32 are for the inner row of contacts 33 and. thebinding screws 33 are for the outer row of contacts 30. The bindingscrews 32 and 33 have difierent diameters so that the eyelet or lugfastened on the end of the wire which is intended to be fastened to theinner contact 30 will not fit over the outer contact screw 33, thusinsuring that the wires of desired polarity are connected to the innerand outer contacts. The binding screws 33 for the binding posts 23 and25 are likewise of different diameters for the same purpose.

In order that the switch arms l5 and i6 may be properly supported whenthe switch is in its 01f position, vention is provided with a pair ofposts 35 which are also driven in the insulating disk l butwhich do notproject from the back surface thereof and are therefore electricallydead.

In order that the switch arm It may pass smoothly from one contact inthe outer row to the next, the spaces between the contacts 30 arebridged by plugs 33 driven into the insulating disk I!) and having aheight substantially equal to the height of the contacts 30. These plugspreferably terminate short of the rear face of the disk l3 and the widthof the ends of the switch arm 56 is such that the advancing corner doesnot engage the next contact until the trailing corner has disengaged thecontact which it is leaving. V I

Rotation of the shaft i3 is limited so that the switch arms may not passtacts 30 on the one side and the posts 35 on the other side by stop pins31 driven into the insulating disk Ill and engaging the switch arm IS.

The binding post 25-has an ear 38 secured to a pin 39 which extends intothe semicircular contact 21 and carries current therefrom to the bindingpost. The binding post 24 is similarly connected to-the semicircularcontact 26.

In order'to hold the switch arms in adjusted position against casualmovement and also to center the switch arms l and I6 over their contacts30, the disk 23 is provided with a plurality' of spaced notches 40adapted to be engaged by a detent spring ll carried'- by a post 42. Thispost is driven into-an aper'ture in the insulating disk lll;and, afterit is rotated to adjust the pressure of the spring on the disk 23. it islocked .in the proper position by a pin the switch of the present in-'beyond the end con-- 33 passing into the post radially through the diskl0. 7

It will be understood from the above that the switch of the presentinvention can be assembled on the disk l0 and the parts adjusted andtested before the casing i9 is applied, the shaft M being turned forthis purpose by loosely applying the handle IT or by applying a suitabletool. After the switch is adjusted, the casing with its dial is mountedon the disk and secured thereon by a screw 33, after which the handle I!may be placed on the end of the shaft l4 and secured against turning bya pin 35.

The casing is provided with apertured ears 36 by means of which it maybe mounted on an instrument board of the like.

In order to hold the contacts against turning after they have beendriven into the insulat- Variations and modifications may be made withinthe scope of this invention and portions of the improvements may be usedwithout others.

Having thus described the invention, what is claimed as new and forwhich it is desired to obtain Letters Patent, is:--

l. A rotary switch comprising a disk of insulating material having anaperture at the center thereof and a plurality of spaced aperturesarranged on an arc concentric with the disk; a bearing held in saidcentral aperture by a drivefit; a shaft carried by said bearing; aswitch arm carried by said shaft located at the front side of the disk;and a plurality of contacts held in the arcuately arranged apertures bya drive-fit and projecting through the disk for engagement by saidswitcharm, said contacts having portions projecting from the back sideof the disk and constituting binding posts, there being binding screwsapplied laterally of said posts.

2. A rotary switch comprising a disk of insulating material having anaperture at the center thereof and a plurality of spaced aperturesarranged on an arc concentric with the disk; a.

3. A rotary switch comprising a disk of insulating material having anaperture at the center thereof and a plurality of spaced aperturesarranged on. an arc concentric with the disk; a bearing driven into saidcentral aperture; a shaft carried by said bearing; a switch arm carriedby said shaft located at the front side of the disk; and a plurality ofcontacts driven into the arcuately arranged apertures from the back sideof the disk and projecting through the disk for engagement by saidswitch arm, said contacts being cylindrical and having flattenedportions projecting from the back face of the disk and provided with abinding screw.

4. A rotary switch comprising a disk of insulation having an aperture inthe center thereof;

driven in said central aperture; a'sbaft carried by said bearing, saidshaft having an annular blades insulated groove located in a partthereof extending into the bearing; a pin in the bearing extending intosaid groove to hold the shaft in the bearing against endwise movement;and a switch arm carried by the shaft for engaging said contacts.

5. A rotary switch comprising a disk of insulation having an aperture inthe center thereof; a bearing in said aperture; a shaft carried by saidbearing; two arcuate rows of spaced contacts carried by one-half thedisk and concentric therewith, one of said rows being located inwardlyof the other; a pair of semicircular contact bars carried by the otherhalf of the disk and concentric therewith, one of said bars beinglocated inwardly of the other; and two switch from each other andcarried by said shaft, one switch blade closing circuits between theinner contact bar and the contacts of the inner row and the otherclosing circuits between the outer contact barand the outer row ofcontacts.

6. A rotary switch comprising a disk of insulating material; two arcuaterows of contact points concentrically arranged on the disk, one rowwithin the other; two arcuate contact bars also concentric with the diskand one inwardly spaced from the other, said bars and points beingrespectively at diametrically opposite sides of the disk; and two switchblades rotatably mounted in the center of the disk insulated from eachother, and each engaging one arcuate contact bar and the contacts of oneof said arcuate rows of contacts, said blades extending diametricallyacross the center of the disk.

'7. A rotary switch comprising a disk of. insulating material; twosimilarly arcuate rows of contacts concentrically arranged on the diskto project from the face thereof, one row within the other, there beingthe same number of con tacts in-both rows, and the contacts of the innerrow being closely adjacent each other and the contacts in the outer rowbeing substantially spaced from each other; two similar switch armsrotatably mounted on said disk, one to engage each row of contacts;andmetal plugs located in the outer row of contacts and alternating withthe contacts of the row to bridge the gap between the contacts of theouter row and permit the switch arm engaging the same to slide smoothlyfrom one contact to the next.

8. A rotary switch comprising a disk of insulating material; a pluralityof spaced contacts carried by said disk; a shaft rotatably mounted onthe disk; a switch blade carried by said shaft; a notched disk carriedby the shaft; a post mounted on said disk of insulating material andprojecting therefrom; and a spring arm carried by said post and engagingthe notches of said disk to hold the shaft and switch arm in adjustedposition against casual movement.

9. A rotary switch comprising a disk of insulating material; twosimilarly arcuate rows of contacts concentrically arranged on the diskto project from the face thereof, one row within the other, there beingthe same number of contacts in both rows, and the contacts of the innerrow being closely adjacent each other and the contacts in the outer rowbeing substantially spaced from each other; two similar switch armsrotatably mounted on said disk, one to engage each row of contacts; andplugs located in the outer row of contacts and alternating with thecontacts tact 'is substantially as close to the adjoining plugs as acontact in the inner arcuate row is to

